Experimental studies

Question 1

What is Randomization?

Answer 1

Assignment of a patient to a study group by chance.

Question 2

Experimental studies main characteristics

Answer 2

1. Manipulation of the study factor by investigators (M)
2. Randomization of study subjects into treatment and control (R)

Other
3. Equipois: Uncertainty about risk and benefits of test treatment. Making it ethical, balanced.

Question 3

How are subjects selected

Answer 3

1. Inclusion and exclusion very precise.
2. Signed consent
3. Randomization

Question 4

Advantages RCT

Answer 4

1. Control treatment
2. Reduce selection bias
   2.1 Other bias too
3. Balanced groups or distribution of confounders
4. Stronger temporal sequence
5. Statistical hypothesis testing

Question 5

Disadvantages of RCT

Answer 5

1. May not represent or be effective in all community
2. Intense monitoring not real world setting
3. Potential unblinding
4. Cost and duration
5. Long term rare side effects
6. Limited comparisons of treatment

Question 6

How to control bias in RCT

Answer 6

1. Blinding or Masking (Unaware of which subjects are in which group (unblinded, single blind, double blind, triple blind). (detection bias)
   1.1. They use placebo to achieve blinding.
2. Randomization (selection bias)
3. Standarized data collection (measurement/info bias)
4. Intention to treat Analysis. Includes all the participants in the groups even if they leave. (attrition)

Question 7

Ethical issues of RCT

Answer 7

1. Consent of participants (Not having consent)
2. Must be genuine doubt about efficacy (not acheiving equipoise)
3. Stopping rules (if treatment is beneficial or toxic not stopping)

Question 8

Formulas for RCT

Answer 8

1. Cummulative incidence
2. Incidence density

Other
1. Risk Ratio
2. Rate ratio
3. Risk difference
4. Number needed to treat